Switchman + Instructure Jobs Compatibility Gem

If you are using the Switchman and Instructure Jobs gems in your application, simply include this gem to make background jobs aware of sharding.

Some high-level features this gem provides to make this work:

• Awareness on the Switchman side (inside shards) that shards have associated DJ shards that need to be activated when trying to talk to the DJ tables (lib/switchman_inst_jobs/switchman)
• Awareness on the DJ side that jobs run within a given shard context that can be loaded from the config and need to activate the shards jobs live on before running (lib/switchman_inst_jobs/delayed)

Requirements

• Ruby 2.7+
• Rails 6.1+

Installation

First ensure that you have installed both Switchman and Instucture Jobs gems, including their database migrations.

Add this line to your application's Gemfile:

gem 'switchman-inst-jobs'

And then execute:

bundle

Or install it yourself like so:

gem install switchman-inst-jobs

You will also want to install the database migration necessary to include the associated shard for any queued jobs:

bundle exec rake switchman_inst_jobs:install:migrations
bundle exec rake db:migrate

You can continue to use inst-jobs settings like you would normally. There is one inst-jobs setting you may want to configure in your application though:

Delayed::Settings.worker_procname_prefix = lambda do
  "#{Switchman::Shard.current(Delayed::Job).id}~"
end

Development

A simple docker environment has been provided for spinning up and testing this gem with multiple versions of Ruby. This requires docker and docker-compose to be installed. To get started, run the following:

docker-compose build --pull
docker-compose up -d postgres
docker-compose run --rm app

This will install the gem in a docker image with all versions of Ruby installed, and install all gem dependencies in the Ruby 2.7 set of gems. It will also download and spin up a PostgreSQL container for use with specs.

The first build will take a long time, however, docker images and gems are cached, making additional runs significantly faster.

To run individual specs in a development workflow, you're going to want to have your file system mounted into the container:

cp docker-compose.override.example.yml docker-compose.override.yml

Then you're going to want to have a console open so that you can do a fast-feedback loop while making changes:

docker-compose run --rm app /bin/bash -l -c
# you're inside the container shell now
bundle install
bundle exec rspec
bundle exec rspec spec/lib/delayed/worker/health_check_spec.rb

Watch your tests fail, tweak things, run the spec again, etc.

Making a new Release

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then just run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/instructure/switchman-inst-jobs.

License

The gem is available as open source under the terms of the MIT License.